1. Field of the Invention
The present invention is directed to porous groyne-like or porous screen structures and method for their use in reclaiming beaches, shoreline areas and other land masses which are subject to erosion by natural forces and, more specifically, to porous screen structures which are vertically adjustable during use, thereby allowing the screens to be systematically raised as reclamation progresses from the buildup of silt, sand, shells, dirt, twigs and branches, grasses and other materials.
2. Discussion of the Related Art
Beach and other shoreline erosion, especially in coastal areas, is a major concern to property owners who have residences or establishments which are situated in close proximity to the shoreline. Not only is there a tremendous personal and economic loss caused by damage to, or loss of, real estate, housing and commercial buildings by shoreline or beach erosion, but there is also recreational loss of waterfront property which adversely affects the general public.
To deter coastal erosion in many areas, large seawalls are constructed to prevent high tides from reaching land and property. Such structures are costly and are only practical when population densities make it economically reasonable to construct them. Further, such structures have an adverse effect on the natural appearance of the shoreline and, in many areas, cannot be practically constructed.
Other methods of shoreline reclamation include creating jetties or artificial barriers or reefs which extend from the shoreline. These structures are permanent installations and are generally utilized to prevent sand along coastal areas from washing out to sea by wave action. Like seawalls, however, such structures are costly to construct and maintain and, in some areas, are not appropriate for use due to the shoreline configuration, prevailing currents or tidal activity and the like. Also, such structures create a safety hazard in areas where recreational activity is anticipated.
A further method for reclaiming shoreline areas and preventing erosion is the placement of off-shore, underwater barriers. Often, large porous structures are placed along a sea floor or riverbed at some distance from the existing shoreline. The structures are provided to break wave, current or tidal action thereby creating a zone of low velocity water flow adjacent a beach or riverbank so that sand, silt and other particulate material will settle out of the water before being conveyed by fluid currents out from the shoreline. Again, such outer barriers are only appropriately used in some locations and are not appropriate for use in many locations and may be objectionable for use in some areas due to the adverse affect on aquatic life.
Other methods which are widely used to reclaim shorelines or beaches are dredging and sand importation. When major dunes along a shoreline are damaged or washed away during heavy storms, it is often necessary to import new dirt and sand to re-establish the dunes to provide a natural barrier to tidal activity. Dredgers are commonly utilized to pump sand from a sea floor or riverbed to build up natural barriers. Such methods of shoreline reclamation, however, are temporary measures, at best, and do not provide a long-term solution to shoreline erosion. Further, such restoration methods are extremely costly and are not practical in many locations.
In view of the foregoing, there is a need to provide a method and apparatus for economically reclaiming damaged shorelines, and other land mass beach areas which can be practically used without an adverse effect to either land or water environments. In U.S. Pat. Nos. 1,969,123 and 4,710,056, methods and structures for beach restoration are disclosed which utilize netting for purposes of trapping sand, shells and other particulate matter carried by wave action. Nets are extended outwardly from the shoreline and are left in place until a buildup of sand and other particulate matter is established after which the nets, which may be buried several feet or more in the newly collected material, are withdrawn by winches or other means. The removal of the netting material can adversely affect the restored shoreline by creating trenches or furrows which form natural channels in which water flows away from the shoreline thereby conveying particulate matter back to a body of water.
Other examples of porous shoreline reclamation structures are disclosed in U.S. Pat. No. 227,483 to Case, U.S. Pat. No. 1,060,357 to Nies, U.S. Pat. No. 1,948,639 to Youngberg, U.S. Pat. No. 1,646,168 to Pringle, U.S. Pat. Nos. 2,097,342 and 2,341,515 to Reheld, U.S. Pat. No. 2,135,337 to Herbert, Jr., U.S. Pat. No. 2,662,378 to Schmitt, et al., U.S. Pat. No. 3,564,853 to Csiszar, U.S. Pat. No. 4,861,193 to Newkirk, U.S. Pat. No. 4,118,937 to Mansen, U.S. Pat. No. 4,738,563 to Clark, U.S. Pat. No. 5,108,222 to Jansson, et al., and U.S. Pat. No. 5,255,997 to Bailey, et al.
The present invention is directed to a method and apparatus for reclaiming shoreline, beach and offshore areas which includes the installation of removable groyne-like structures having a plurality of posts or stanchions which are embedded in a sea floor, or in other areas, so as to extend in spaced relationship outwardly from a shoreline and between which are mounted one or a plurality of porous screens. As used herein, the term shoreline refers to both land and offshore bottom areas including beaches and banks situated along lakes, rivers, inlets, bays, seas, oceans and the like, it being the express purpose of the present invention to build up solid material deposits both on and offshore. The screens may be formed of any suitable materials having a plurality of openings therein and, in preferred embodiments, are formed of flexible elements such as chain link, conventional netting, geo-textiles, expanded plastics, nylon meshes, knitted and woven fabrics and the like. In some embodiments, the openings may be created in somewhat non-flexible materials such as open slatted wooden or plastic structures.
The screens are supported relative to the stanchions and have lower edges which are designed to rest on and become temporarily embedded in deposited material forming a new land mass. The screens further include means for periodically and systematically elevating at least the lower portion thereof to thereby prevent the screens from being too deeply embedded within newly deposited particulate material. Such means may include tie lines, take-up reels, hoists and the like which are used to elevate the screens by either manual or motor operated devices. Hoist or winch devices may be mounted at a common point for each structure or may be separately attached to spaced stanchions along a structure.
To facilitate the manner in which the screens are periodically raised, in one embodiment, each screen is secured at its opposite ends to rings or loop members which encircle and are vertically adjustably moveable along at least a pair of spaced stanchions which support each screen. Thus, when screens are extended or deployed in generally end-to-end relationship, each end is secured to a separate stanchion. In some embodiments the ends of the screens may partially overlap one another. With some of the groyne structures of the invention, many of the stanchions will be deployed in pairs extending in spaced relationship to one another such that one screen may be vertically adjusted without effecting the placement of adjacent screens. In other embodiments, screens may extend between three or more stanchions with the ends of the screens secured to common stanchions.
To further facilitate the manner in which the screens of the invention are vertically adjusted and to strengthen the integrity of the groynes of the invention, each screen may be secured at its opposite ends to one or more tubes or sleeves which are slidable disposed about the spaced stanchions. Elevation of the screens may be accomplished by lifting or elevating the sleeves relative to the stanchions. In preferred embodiments, each screen is secured at its ends to stanchions not supporting other screens, however, in some embodiments the sleeves may support adjacent screens in end-to-end relationship.
To rigidify the screens when flexible materials are used, cables, wire rope or similar elements are provided at least along the upper, lower and end edges or selvages of each screen or screen sections. The longitudinal cables are secured to the vertically extending end cables so that, by clamping the vertical cables to the stanchions, tension is applied to the longitudinal cables to thereby pull the cables, and thus the screen material, taut between the stanchions.
As a further improvement, in some embodiments, each screen may be sub-divided into separate vertical sections, each of which may be secured to a plurality of separate sleeves movably mounted on end supporting stanchions. In this manner, as the screen sections are raised, the uppermost sections can be removed from the groyne structures, as is necessary.
The screens of the present invention may include non-uniform mesh openings between the lower and upper portions thereof. In some embodiments, a plurality of screen sections are vertically joined with respect to one another with the lower screen sections having mesh openings of a smaller dimension than each subsequent vertical section. In other embodiments, the screen sections are not joined and are independently supported and moved. Typical openings may range from approximately xe2x85x9xe2x80x3 in the lowermost screen sections to 1xe2x80x3 or more in uppermost screen sections. In one embodiment, four screen sections are disclosed, although the number of screen sections may be varied depending upon the requirements of a particular reclamation site.
The screen sections are elevated utilizing lifting ropes or lines which are secured such as along the lower edges of the sections and/or at spaced elevated locations along the screens, such as at the intersection of the various vertical sections of a screen. Alternatively, or in addition to, the screen sections may be elevated by lifting rings or sleeves which connect the screens to the stanchions.
Utilizing the methodology of the present invention, a plurality of spaced groyne structures are positioned so as to extend outwardly from a shoreline in spaced relationship with respect to one another. The orientation between the groyne structures and their angular relationship with respect to other areas or masses, such as along a shoreline, will be dictated by the specifics of a given area including currents, tidal activity and winds. Once the screen or screens have been secured to the spaced stanchions, the lower portions of the screens are periodically elevated, as deposits form at the base of the screen sections, so as to not become too deeply embedded in the newly deposited material.
Preferably, the lower portions or lower edges of the screens are elevated such that a portion of the lower edges are retained within material deposited, so that the material deposited retains the lower edges of the screens on the land mass or sea floor. The structures of the present invention further facilitate the raising of the screens and securing of the screens in a raised position during periods when it is necessary, for example, so as not to interfere with movement of aquatic or other life. Following reclamation, the structures may be easily removed without disturbing the contour of the reclaimed land.
It is a primary object of the present invention to provide a method and apparatus for economically reclaiming land including along shorelines and offshore areas of oceans, gulfs, inlets, bays, rivers, lakes as well as other areas where currents, tidal and/or wind activity is experienced.
It is a further object of the present invention to provide groyne structures and a method for installing such structures in such a manner that the structures may be temporarily installed and removed after land has been reclaimed without disturbing the natural contour of the reclaimed land.
It is yet a further object of the present invention to provide groyne structures which may be utilized to reclaim land, such as along a shoreline, which are environmentally compatible and which may be periodically adjusted so as to not adversely affect the buildup of deposited materials.
It is also an object of the present invention to provide groyne structures which may be utilized to reclaim land, such as along a shoreline, which, in some embodiments, include screens which may be individually adjusted, be formed of independently moveable sections and/or be constructed of materials having sections of different porosity or opening sizes such that the smaller openings in the screen are provided along lower sections thereof to facilitate buildup of fine particles along the base of the screens.
It is another object of the present invention to provide a method and apparatus for economically reclaiming land including along shorelines and offshore areas of oceans, gulfs, inlets, bays, rivers and the like wherein the buildup of material deposits is utilized to temporarily retain the lower portions of the screens in position.